OMAP3630: PM: Erratum i583: disable coreoff if < ES1.2

Limitation i583: Self_Refresh Exit issue after OFF mode

Issue:
When device is waking up from OFF mode, then SDRC state machine sends
inappropriate sequence violating JEDEC standards.

Impact:
OMAP3630 < ES1.2 is impacted as follows depending on the platform:
CS0: for 38.4MHz as internal sysclk, DDR content seen to be stable, while
	for all other sysclk frequencies, varied levels of instability
	seen based on varied parameters.
CS1: impacted

This patch takes option #3 as recommended by the Silicon erratum:
Avoid core power domain transitioning to OFF mode. Power consumption
impact is expected in this case.
To do this, we route core OFF requests to RET request on the impacted
revisions of silicon.

Acked-by: Jean Pihet <j-pihet@ti.com>

[nm@ti.com: rebased the code to 2.6.37-rc2- short circuit code changed a bit]
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Eduardo Valentin <eduardo.valentin@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

1 files changed, 22 insertions, 3 deletions

diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 74bc15e71e9f..a81ed251e667 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -917,12 +917,29 @@ void omap3_pm_off_mode_enable(int enable)
 		state = PWRDM_POWER_RET;
 
 #ifdef CONFIG_CPU_IDLE
-	omap3_cpuidle_update_states(state, state);
+	/*
+	 * Erratum i583: implementation for ES rev < Es1.2 on 3630. We cannot
+	 * enable OFF mode in a stable form for previous revisions, restrict
+	 * instead to RET
+	 */
+	if (IS_PM34XX_ERRATUM(PM_SDRC_WAKEUP_ERRATUM_i583))
+		omap3_cpuidle_update_states(state, PWRDM_POWER_RET);
+	else
+		omap3_cpuidle_update_states(state, state);
 #endif
 
 	list_for_each_entry(pwrst, &pwrst_list, node) {
-		pwrst->next_state = state;
-		omap_set_pwrdm_state(pwrst->pwrdm, state);
+		if (IS_PM34XX_ERRATUM(PM_SDRC_WAKEUP_ERRATUM_i583) &&
+				pwrst->pwrdm == core_pwrdm &&
+				state == PWRDM_POWER_OFF) {
+			pwrst->next_state = PWRDM_POWER_RET;
+			WARN_ONCE(1,
+				"%s: Core OFF disabled due to errata i583\n",
+				__func__);
+		} else {
+			pwrst->next_state = state;
+		}
+		omap_set_pwrdm_state(pwrst->pwrdm, pwrst->next_state);
 	}
 }
 
@@ -1000,6 +1017,8 @@ static void __init pm_errata_configure(void)
 		pm34xx_errata |= PM_RTA_ERRATUM_i608;
 		/* Enable the l2 cache toggling in sleep logic */
 		enable_omap3630_toggle_l2_on_restore();
+		if (omap_rev() < OMAP3630_REV_ES1_2)
+			pm34xx_errata |= PM_SDRC_WAKEUP_ERRATUM_i583;
 	}
 }